Page 193 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

LEED Ener gy and Atmospher e 171

LCGWP: Lifecycle Direct Global Warming Potential (lbCO /Ton-Year)
2
GWPr: Global Warming Potential of Refrigerant (0 to 12,000 lbCO /lbr)
2
ODPr: Ozone Depletion Potential of Refrigerant (0 to 0.2 lbCFC /lbr)
11
Lr: Refrigerant Leakage Rate (0.5% to 2.0%; default of 2% unless otherwise demonstrated)
Mr: End-of-life Refrigerant Loss (2% to 10%; default of 10% unless otherwise demonstrated)
Rc: Refrigerant Charge (0.5 to 5.0 lb of refrigerant per ton of gross ARI rated cooling capacity)
Life: Equipment Life (default based on equipment type, unless otherwise demonstrated)
For multiple types of equipment, a weighted average of all base building level HVAC&R
equipment shall be applied using the following formula:
[∑ (LCGWP + LCODP × 100,000) × Qunit ]/Qtotal ≤ 100

Where:
Qunit = Gross ARI rated cooling capacity of an individual HVAC or refrigeration unit
(Tons)
Qtotal = Total gross ARI rated cooling capacity of all HVAC or refrigeration
ALL OPTIONS
Small HVAC units (defined as containing less than 0.5 lbs of refrigerant), and other
equipment such as standard refrigerators, small water coolers, and any other cooling
equipment that contains less than 0.5 lbs of refrigerant, are not considered part of the “base
building” system and are not subject to the requirements of this credit.
AND
Do not operate or install fire suppression systems that contain ozone-depleting substances
(CFCs, HCFCs or halons).
Potential Technologies and Strategies
Design and operate the facility without mechanical cooling and refrigeration equipment.
Where mechanical cooling is used, utilize base building HVAC and refrigeration systems for
the refrigeration cycle that minimize direct impact on ozone depletion and climate change.
Select HVAC&R equipment with reduced refrigerant charge and increased equipment life.
Maintain equipment to prevent leakage of refrigerant to the atmosphere. Utilize fire
suppression systems that do not contain HCFCs or halons.

Calculations and Considerations
Two issues must be addressed to fulfill the requirements of this credit. The first deals
with the refrigerant processes in heating, ventilation, air conditioning, and refrigeration
(HVAC&R) systems, and the second deals with fire suppression. The two options listed
in the credit are the two options for HVAC&R alternatives, and one of these must be
met. The last item listed in the Requirements section is for fire suppression systems and
must be abided by in all cases.
As mentioned in EA prerequisite 3, CFCs (chlorofluorocarbons) are being phased
out due to their potential impact on the ozone levels in the stratosphere. (Many of these
CFCs and other refrigerants commonly go by the DuPont trademark name Freon.)
However, some of the alternative compounds may also impact the stratospheric ozone,
but not necessarily to the extent that the CFCs do. Two examples of alternatives are the
groups of chemicals referred to as the hydrochlorofluorocarbons (HCFCs) and
hydrofluorocarbons (HFCs). HCFCs are similar to CFCs but also contain some hydrogen
atoms instead of chlorine atoms and therefore have a lower potential for ozone depletion
than do the CFCs. HFCs are also similar to HCFCs and CFCs but with no chlorine
atoms, and therefore the ozone depletion potential of HFCs is negligible.